Current three-dimensional (3D) projection imaging technologies include spectroscopically stereoscopic display, volumetric 3D display, holographic 3D display, and the like. The spectroscopically stereoscopic display means that a retina receives two images with parallax, and by distinguishing between different areas of an object as to being bright/dark, being in front/in rear, and being near/far, one “sees” a stereoscopic object, which is usually realized by a polariscope, e.g. 3D stereoscopic glasses, 3D stereoscopic movies, and the like. The volumetric 3D display creates a 3D stereoscopic image with a true stereoscopic effect in a certain transparent solid from a plurality of two-dimensional images, by using techniques like high-speed motion of optics and high-frequency light projection, such as a volumetric 3D display. Both the spectroscopically stereoscopic display and the volumetric 3D display rely on a solid medium in achieving 3D display. The holographic 3D image display forms a complex holographic light field by interference of two light beams with each other; however, the holographic light field needs to be holographically recorded first, that is, information such as lightness of the object and the depth of field is recorded in a holographic material to form a hologram, and then reconstruction of 3D information is performed. Although dynamic display of a hologram is possible by using continuous films, the imaging angle of an image is still within the films.